Irrigation In Polytunnels

The majority of vegetables are 80 to 95 percent water. So next time you look at your lovely vegetables in your tunnel or glasshouse think of them as little sacks of water, flavoured and full of vitamins.

But remember, if the supply of water fails your vegetables yield and quality will suffer rapidly. In the high temperatures found in polytunnels and glasshouses it’s very important to irrigate on a regular basis and guarantee a reliable supply.

The two most common methods of irrigation are overhead irrigation and ground level irrigation. Overhead is by far the simplest method. Water is released from sprinklers suspended from the roof of the tunnel or the glasshouse. These form a mist which saturates everything in the tunnel.

Some draw backs of overhead irrigation: water is wasted as it not only falls on the beds and plants, but also the walkways through your greenhouse as well as work areas: sun spots are more likely to occur as the result of droplets forming on the foliage: and a large number of plants prefer being watered into the root as appose to directly onto the plant itself.

Ground irrigation is a much more effective method. Lines of perforated pipe lay on top of the vegetables beds. Built in regulators in the perforated pipe leak out a set amount of water per hour. This allows even irrigation across the bed and more importantly directly into the root.

However it does have its drawbacks also. More pipes + more fitting = higher costs. Also, as the pipes sit on top of the beds they sometimes can be in the way during weeding and planting.

Don’t forget to automate your irrigation system if you’re away for long periods, therefore guaranteeing that your plants get their daily dose. Tap timers are a simple and effective solution. These can be gotten in many garden centres and DIY shops and are very easy to install.